Birefringence angle estimates (in degrees) versus the maximum multipole considered. Only (1σ) statistical uncertainties are shown here; with systematic errors discussed later. Commander is shown in red, NILC in orange, SEVEM in green, SMICA (full-mission data) in blue, and SMICA (half-mission data) in cyan. Dot symbols refer to the estimates obtained with the estimator. Star symbols refer to estimates coming from and squares are obtained through the combination of and .